He needs to be examined by a doctor for the source of this fluid. A search has to be made for any small discharging spot (called sinus
in medical terminology). If discharge is not from a spot and it is from a diffuse area then it is likely to be sweat as you are suspecting. The sweat glands are distributed all over the skin and density of these glands vary in different parts of body and in different individuals. It doesn't really point to a specific disease entity and I would consider it as a normal variant.